Compositions that produce lather for shaving have been known for many decades. One type of known shaving composition that have been used for years are those whisked with a brush to incorporate air and thereby generate lather.
Another type of known lather producing shaving composition are those aerosol shaving compositions containing volatile organic liquids under super atmospheric pressure. Such compositions are disclosed in U.S. Pat. No. 2,655,480 to Spitzer et al. In these lather producing compositions, the vapor pressure of the volatile liquids is substantial, say 25 to 40 p.s.i.g. so that the compositions are immediately converted to lather when released from the aerosol container to the atmosphere.
A more recent type of lather producing shaving composition is the gel lather producing composition disclosed in U.S. Pat. No. 3,541,581 to Monson. In the composition of this patent there are employed organic liquids with vapor pressures of 6 to 14 p.s.i.g. According to Monson patent, the Monson compositions when released from their container would quickly expand to a lather if not for the inclusion of a gelling agent which restrains lather formation until the shaving composition is applied to the skin in the form of a gel.
More particularly, the Monson compositions are postfoaming shaving gel compositions that are dispensed as gels, but produce a lather when rubbed on the face. The compositions comprise a soap solution, a gelling agent, and an organic liquid having a vapor pressure from about 6 to about 14 p.s.i.g. at a temperature from about 90.degree. to 100.degree. F. The organic liquid is the post-foaming agent.
In order to dispense Monson's compositions with their super-atmospheric vapor pressures in the form of gels, it is necessary to employ an especially complex and expensive-aerosol container, that in addition to the usual components also includes a bag or piston or equivalent device, as shown in Monson's FIG. 4 of the Monson patent.
While Monson states that his post-foaming gels can be packaged in collapsible metal tubes, this is not practical. Because of the super-atmospheric pressure of the compositions, it is necessary to use an aerosol valve and dispensing spout. If a tube cap were used, the composition would continue to gush from the container until the cap were screwed into place. Further, the crimped end of the collapsible tube would unravel and pop open under the sustained pressure of the composition. In addition, the pressure would maintain the collapsible metal tube in a constantly expanded state, regardless of the amount of material in the tube. As a consequence, as the contents were emptied, the gel would tend to expand to fill the tube, and then be expelled as an aerated gel or lather.
The Monson compositions because of their above atmospheric vapor pressure can not be exposed to elevated temperature in storage, shipping and use without causing problems of premature expansion.